Toughened impact-resistant nylon-based engineering plastics and methods for making the same

Abstract

The application discloses a kind of toughened impact-resistant nylon-based engineering plastics and preparation method thereof, belong to high polymer composite material technical field.The method is prepared mesoporous hollow SiO2 particle with polyacrylic acid as soft template, through vacuum negative pressure loading pentaerythritol triacrylate (PETA) photo-curing resin and photo-initiator, then modified to obtain composite filler by silane coupling agent;After it is melt blended with nylon resin, antioxidant and lubricant, extrusion granulation, PETA is crosslinked to form three-dimensional network structure by ultraviolet light curing, and the composite material is prepared.The application realizes rigid reinforcement by mesoporous hollow SiO2, and simultaneously dissipates impact energy efficiently through crosslinking network between particles, solves the problem that reinforcement and toughening are difficult to be considered in traditional nylon modification.The obtained material has uniform inorganic filler dispersion, and has high tensile strength and excellent toughness, and balanced mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically relating to a toughened and impact-resistant nylon-based engineering plastic and its preparation method. Background Technology

[0002] Nylon (PA), as a general-purpose engineering plastic with excellent comprehensive properties, is widely used in automotive parts, electronic and electrical housings, mechanical structural components, and rail transportation due to its good mechanical strength, wear resistance, chemical corrosion resistance, and processability. However, ordinary nylon materials have inherent defects such as poor low-temperature toughness, low notched impact strength, and insufficient resistance to external impact. Under high mechanical loads and complex impact conditions, it is prone to brittle fracture, which greatly limits the expansion of its high-end application scenarios.

[0003] Currently, the industry mostly uses inorganic rigid particles as fillers to reinforce nylon materials. Common fillers include calcium carbonate, talc, solid silica, and glass microspheres. These inorganic particles can improve the tensile strength, flexural modulus, and dimensional stability of nylon. However, inorganic particles have poor compatibility with the nylon matrix interface, which can easily lead to problems such as agglomeration and interface voids. Under external force, stress concentration points are formed, resulting in a significant decrease in the toughness of the material. It is impossible to achieve both reinforcement and toughening effects. If only elastomer toughening agents are added, although the impact performance can be improved, the rigidity, heat resistance, and dimensional stability of nylon will be significantly reduced, resulting in an imbalance of the material's mechanical properties.

[0004] Mesoporous hollow SiO2 particles have abundant surface pores and high specific surface area, which can be used as functional carriers to load organic components. However, when directly blended with nylon, they are prone to agglomeration and weak interfacial bonding, making it impossible to achieve effective stress transfer and impact energy dissipation. This still cannot solve the technical problem of the contradiction between nylon reinforcement and toughening. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a toughened and impact-resistant nylon-based engineering plastic and its preparation method. Using mesoporous hollow SiO2 as a carrier, PETA photocurable resin is fully adhered to the surface and interior of the mesoporous hollow SiO2. After surface modification, it is blended with nylon and then cured by ultraviolet light, causing the PETA loaded on the mesoporous hollow SiO2 to undergo a cross-linking reaction, forming a continuous three-dimensional cross-linked network. This simultaneously achieves inorganic particle reinforcement and overall cross-linking toughening, solving the problem that traditional inorganic filled nylons cannot simultaneously achieve both strength and toughness.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a toughened and impact-resistant nylon-based engineering plastic includes the following steps: S1. Preparation of mesoporous hollow SiO2 particles: By mass: Dissolve 1-1.5 parts of polyacrylic acid (PAA, average molecular weight 5000) in 6-8 parts of 25% ammonia water, add dropwise to 80-100 parts of anhydrous ethanol, then add 5-6 parts of tetraethyl orthosilicate (TEOS), one part every 1 hour, and stir for a total of 8-10 hours to uniformly coat SiO2 on the surface of PAA micelles; centrifuge, wash, and obtain mesoporous hollow SiO2 particles.

[0007] S2. PETA resin adhesion load Add 20-30 parts of anhydrous ethanol to the mesoporous hollow SiO2 particles from step S1; add 5-8 parts of pentaerythritol triacrylate (PETA) and 0.3-0.5 parts of 1-hydroxycyclohexylphenyl ketone (HCPK) according to the ratio, and stir continuously at 600-800 r / min to obtain a mixed system; place the mixed system under vacuum of -0.08~-0.09 MPa for 2-3 hours, using negative pressure to fully impregnate and attach PETA resin to the surface and interior of the mesoporous hollow SiO2 particles, ensuring that the resin and inorganic particles are tightly bonded; after restoring normal pressure, add 0.5-0.8 parts of silane coupling agent, and stir at 100-150 r / min for 1-2 hours; then separate the solid particles by centrifugal filtration or vacuum filtration, and wash with a small amount of anhydrous ethanol 1-2 times to remove unattached free PETA resin, and dry to obtain PETA-attached and loaded mesoporous hollow SiO2 particles, thus obtaining the modified filler. S3. Melt blending granulation Add 65-85 parts of nylon resin, 8-10 parts of modified filler, 0.2-0.6 parts of antioxidant, and 0.3-0.8 parts of lubricant to a high-speed mixer and mix at room temperature for 10-15 minutes at a stirring speed of 800-1200 r / min until all components are mixed evenly. The mixture is added to a twin-screw extruder, and after melt blending, extrusion, water cooling, and pelletizing, nylon composite pellets are obtained; wherein the temperature of the twin-screw extruder is set as follows: Zone 1: 220-230℃, Zone 2: 230-240℃, Zone 3: 240-250℃, Zone 4: 235-245℃, Head temperature: 240-250℃; Screw speed: 250-350 r / min.

[0008] S4. UV-cured integral crosslinking Nylon composite granules are placed in a UV curing device and cured under UV light for 3-5 minutes. Under the initiation of HCPK, PETA resin attached to the surface and pores of different mesoporous hollow SiO2 particles undergoes free radical polymerization and cross-links with each other, finally obtaining toughened and impact-resistant nylon-based engineering plastics.

[0009] Further optimization of the preparation method for a toughened and impact-resistant nylon-based engineering plastic.

[0010] Preferably, the nylon resin is PA6 or PA66.

[0011] Preferably, the silane coupling agent is selected from one or more of KH550, KH560, and KH570.

[0012] Preferably, the antioxidant is one or a combination of two of 1098 and 168; Preferably, the lubricant is ethylene bis-stearamide or calcium stearate.

[0013] A toughened and impact-resistant nylon-based engineering plastic was obtained using the above method.

[0014] Mechanism of action (1) The mesoporous hollow SiO2 particles have well-developed pores and high specific surface area, which can enable PETA resin to adhere in large quantities and be stably loaded. (2) Mesoporous hollow SiO2 particles, due to their own rigidity, are uniformly dispersed in the nylon matrix as an inorganic reinforcing phase, thereby improving the strength and modulus of the material. (3) PETA resin adheres tightly to the surface and pores of mesoporous hollow SiO2 particles. After UV curing, the PETA on the particles cross-links to form a continuous three-dimensional network, connecting the dispersed inorganic particles into a whole. (4) When subjected to impact, the cross-linked network can quickly disperse stress, dissipate a large amount of energy through plastic deformation, inhibit crack propagation, and achieve significant toughening.

[0015] The beneficial effects of this invention are: (1) The present invention uses mesoporous hollow SiO2 particles as inorganic reinforcing phase. With its unique hollow mesoporous structure and high specific surface area, it plays a rigid particle reinforcing role in the nylon matrix, effectively improving the tensile strength of nylon-based composite materials and making up for the lack of mechanical strength of ordinary nylon.

[0016] (2) Mesoporous hollow SiO2 is used as a carrier to load PETA photocurable resin. Combined with ultraviolet curing process, PETA resin undergoes cross-linking reaction on the surface and internal pores of inorganic particles to form a continuous three-dimensional cross-linked network. Under the action of external force impact, stress is quickly dispersed and impact energy is dissipated in large quantities through plastic deformation of the resin cross-linked phase, which greatly improves the impact toughness of the material at room temperature and low temperature.

[0017] (3) This invention breaks through the technical bottleneck of "strengthening inevitably reduces toughness and increasing toughness inevitably reduces stiffness" in traditional nylon modification. While improving the rigidity and strength of the material, it efficiently dissipates impact energy through the plastic deformation of the three-dimensional cross-linked network, significantly improving the toughness and mechanical properties of the material, and achieving simultaneous improvement of strength and toughness.

[0018] (4) Vacuum negative pressure treatment allows PETA resin to fully enter the internal pores of mesoporous hollow SiO2, resulting in a more robust load and more uniform distribution, thus avoiding the problems of easy migration and precipitation of small organic molecules in the blend system.

[0019] (5) The preparation process is mild and controllable, compatible with the existing nylon twin-screw extrusion granulation process, requires no special equipment, and the UV curing step is simple and efficient, making it suitable for large-scale production. Attached Figure Description

[0020] Figure 1 Transmission electron microscope image of mesoporous hollow SiO2 particles prepared in Example 1; Figure 2 Scanning electron microscope image of mesoporous hollow SiO2 particles prepared in Example 1; Figure 3 The N2 adsorption-desorption isotherm prepared in Example 1; Figure 4 Scanning electron microscope image of the nylon-based engineering plastic prepared in Example 1; Figure 5 The strain curves are for the nylon-based engineering plastics prepared in Example 1 and Comparative Examples 1-3. Detailed Implementation

[0021] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to examples. The following content is merely illustrative and explanatory of the concept of the present invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the inventive concept, all of which should fall within the protection scope of the present invention. The preparation method of the present invention will be described below through specific embodiments.

[0022] Example 1 A method for preparing a toughened and impact-resistant nylon-based engineering plastic includes the following steps: S1. Preparation of mesoporous hollow SiO2 particles By mass: 1 part of polyacrylic acid (PAA, average molecular weight 5000) was dissolved in 6 parts of 25% ammonia water, and added dropwise to 80 parts of anhydrous ethanol. Then 5 parts of tetraethyl orthosilicate (TEOS) were added, one part every 1 hour, and the mixture was stirred and reacted for a total of 8 hours to uniformly coat SiO2 on the surface of PAA micelles. After centrifugation and washing, mesoporous hollow SiO2 particles were obtained.

[0023] S2. PETA resin adhesion load The mesoporous hollow SiO2 particles obtained in step S1 were added to 20 parts of anhydrous ethanol; 5 parts of PETA and 0.3 parts of HCPK were added, and the mixture was stirred continuously at 600 r / min to obtain a mixed system; the mixed system was vacuum treated at a vacuum degree of -0.08 MPa for 2 h to allow the PETA resin to fully impregnate and adhere; after restoring normal pressure, 0.5 parts of KH570 silane coupling agent were added, and the mixture was stirred at 100 r / min for 1 h; the mixture was centrifuged, washed with anhydrous ethanol, and dried to obtain the modified filler.

[0024] S3. Melt blending granulation Weigh out the following components by weight: 75 parts PA6, 8 parts modified filler, 0.2 parts antioxidant 1098, and 0.3 parts ethylene bis-stearamide. Add them to a high-speed mixer and mix at room temperature for 10 minutes at a stirring speed of 800 r / min. The mixture is fed into a twin-screw extruder at 220°C in zone 1, 230°C in zone 2, 240°C in zone 3, 235°C in zone 4, 240°C at the die head, and a screw speed of 250 r / min. After melt blending, extrusion, water cooling, and pelletizing, nylon composite granules are obtained.

[0025] S4. UV curing for overall crosslinking Nylon composite granules were placed in an ultraviolet curing device and cured under ultraviolet light for 3 minutes to obtain toughened and impact-resistant nylon-based engineering plastics.

[0026] Example 2 A method for preparing a toughened and impact-resistant nylon-based engineering plastic includes the following steps: S1. Preparation of mesoporous hollow SiO2 particles By mass: 1.2 parts of polyacrylic acid (PAA, average molecular weight 5000) were dissolved in 7 parts of 25% ammonia water, and added dropwise to 90 parts of anhydrous ethanol. Then 5.5 parts of tetraethyl orthosilicate (TEOS) were added, one part every 1 hour, and the mixture was stirred and reacted for a total of 9 hours to uniformly coat SiO2 on the surface of PAA micelles. After centrifugation and washing, mesoporous hollow SiO2 particles were obtained.

[0027] S2. PETA resin adhesion load Mesoporous hollow SiO2 particles were added to 25 parts of anhydrous ethanol; 6.5 parts of PETA and 0.4 parts of HCPK were added, and the mixture was stirred at 700 r / min; the mixture was then vacuum treated at -0.085 MPa for 2.5 h; 0.7 parts of KH560 silane coupling agent were added, and the mixture was stirred at 120 r / min for 1.5 h; the modified filler was obtained by filtration, washing, and drying.

[0028] S3. Melt blending granulation Weigh out the following components by weight: 80 parts PA66, 9 parts modified filler, 0.4 parts antioxidant 1098 / 168 compound, and 0.5 parts calcium stearate. Mix at room temperature for 12 minutes at a speed of 1000 r / min. Twin-screw extrusion temperatures: Zone 1 225 ℃, Zone 2 235 ℃, Zone 3 245 ℃, Zone 4 240 ℃, Die head 245 ℃, Screw speed 300 r / min, Extrusion granulation.

[0029] S4. UV curing for overall crosslinking Curing under ultraviolet light for 4 minutes yields toughened and impact-resistant nylon-based engineering plastics.

[0030] Example 3 A method for preparing a toughened and impact-resistant nylon-based engineering plastic includes the following steps: S1. Preparation of mesoporous hollow SiO2 particles By mass: 1.5 parts of polyacrylic acid (PAA, average molecular weight 5000) were dissolved in 8 parts of 25% ammonia water, and added dropwise to 100 parts of anhydrous ethanol. Then, 6 parts of tetraethyl orthosilicate (TEOS) were added, one part every 1 hour, and the mixture was stirred and reacted for a total of 10 hours to uniformly coat SiO2 on the surface of PAA micelles. After centrifugation and washing, mesoporous hollow SiO2 particles were obtained.

[0031] S2. PETA resin adhesion load Mesoporous hollow SiO2 particles were added to 30 parts of anhydrous ethanol; 8 parts of PETA and 0.5 parts of HCPK were added, and the mixture was stirred at 800 r / min; the mixture was vacuum treated at -0.09 MPa for 3 h; 0.8 parts of KH550 silane coupling agent were added, and the mixture was stirred at 150 r / min for 2 h; the modified filler was obtained by centrifugation, washing, and drying.

[0032] S3. Melt blending granulation Weigh out the following components by weight: 85 parts PA6, 10 parts modified filler, 0.6 parts antioxidant 168, and 0.8 parts ethylene bis-stearamide. Mix at room temperature for 15 min at a speed of 1200 r / min. Twin-screw extrusion temperatures: Zone 1 230 ℃, Zone 2 240 ℃, Zone 3 250 ℃, Zone 4 245 ℃, Die head 250 ℃, Screw speed 350 r / min, Extrusion granulation.

[0033] S4. UV curing for overall crosslinking Curing under ultraviolet light for 5 minutes yields toughened and impact-resistant nylon-based engineering plastics.

[0034] Comparative Example 1 No modified fillers were added, and the rest of the process was the same as in Example 1.

[0035] Comparative Example 2 Compared with Example 1, PETA and HCPK were not added, and only KH570 modified mesoporous hollow SiO2 particles were used. The other components and preparation steps were exactly the same.

[0036] Comparative Example 3 Compared with Example 1, the UV curing step is omitted, while the remaining components and preparation steps are exactly the same.

[0037] Figure 1 Transmission electron microscopy (TEM) images of mesoporous hollow SiO2 particles clearly show that the prepared SiO2 particles exhibit a regular hollow core-shell structure with intact morphology and no structural collapse or aggregation. This result confirms that using polyacrylic acid (PAA) micelles as a soft template allows for the controllability of SiO2 nucleation and growth processes, successfully preparing structurally controllable mesoporous hollow SiO2 particles. This provides ample surface sites and internal pore space for subsequent loading of PETA photocurable resin.

[0038] Figure 2 Scanning electron microscope images of mesoporous hollow SiO2 particles clearly show that the particles are regular spherical, with a rough surface and abundant mesoporous structure. The particles have excellent monodispersity and no obvious agglomeration or clumping.

[0039] Figure 3 The N2 adsorption-desorption isotherm of mesoporous hollow SiO2 particles exhibits typical type IV isotherm characteristics, accompanied by a significant hysteresis loop, confirming the presence of abundant mesoporous structures within the particles. These particles possess both high specific surface area and large pore volume. The high specific surface area provides numerous adhesion sites for PETA resin, while the large pore volume allows more resin to enter the particle interior, achieving thorough wetting and tight bonding between the resin and inorganic particles.

[0040] Figure 4Scanning electron microscope (SEM) images of nylon-based engineering plastics clearly show that mesoporous hollow SiO2 particles are uniformly dispersed within the nylon matrix, without any particle aggregation, interfacial voids, or delamination. The inorganic particles are tightly bonded to the nylon matrix interface. This result demonstrates that after modification with a silane coupling agent and loading with PETA resin, the surface polarity of the mesoporous hollow SiO2 particles is effectively controlled, significantly improving their interfacial compatibility with the nylon matrix. It also proves that the composite process of this invention can achieve nanoscale uniform dispersion of inorganic components in the matrix, providing microstructural assurance for effective stress transfer and efficient dissipation of impact energy.

[0041] Figure 5 Stress-strain curves of nylon-based engineering plastics in Example 1 and Comparative Examples 1-3; The attached figure shows the stress-strain comparison curves of different samples. The composite material prepared in Example 1 retains the toughness while significantly increasing the strength compared to pure nylon (Comparative Example 1).

[0042] Compared to the system with only modified SiO2 added but no PETA resin (Comparative Example 2) and the system without UV curing (Comparative Example 3), the tensile strength and elongation at break of Example 1 were simultaneously improved, and the curves showed excellent combination characteristics of toughness and strength.

[0043] The curve of pure nylon material in Comparative Example 1 shows the mechanical properties of conventional nylon, with good toughness but low mechanical strength. Comparative Example 2 showed a significant improvement in material rigidity due to the lack of PETA crosslinking phase, but insufficient toughness and a substantial decrease in elongation at break. Comparative Example 3 was not cured with ultraviolet light, so the PETA resin could not form a cross-linked network, resulting in weak stress transmission and energy dissipation capabilities and no significant improvement in mechanical properties. The curve in Example 1 exhibits both high tensile strength and high elongation at break, fully demonstrating that the technical solution of the present invention, which uses mesoporous hollow SiO2 to support PETA resin and then crosslinks it through ultraviolet light curing, can simultaneously achieve material reinforcement and toughening.

Claims

1. A method for preparing a toughened and impact-resistant nylon-based engineering plastic, characterized in that, Includes the following steps: S1 Preparation of mesoporous hollow SiO2 particles: Dissolve 1-1.5 parts of polyacrylic acid in 6-8 parts of 25% ammonia water by mass, add dropwise to 80-100 parts of anhydrous ethanol, then add 5-6 parts of tetraethyl orthosilicate in portions, stir and react for 8-10 hours, and obtain mesoporous hollow SiO2 particles by centrifugation and washing. S2 PETA resin loading: Mesoporous hollow SiO2 particles are dispersed in 20-30 parts of anhydrous ethanol, 5-8 parts of pentaerythritol triacrylate and 0.3-0.5 parts of photoinitiator are added, stirred and then vacuum treated at -0.08~-0.09 MPa for 2-3 hours. 0.5-0.8 parts of silane coupling agent are added to react, and the mixture is separated, washed and dried to obtain the modified filler. S3 Melt Blending: 65-85 parts of nylon resin, 8-10 parts of modified filler, 0.2-0.6 parts of antioxidant, and 0.3-0.8 parts of lubricant are mixed evenly and then granulated by twin-screw extrusion to obtain nylon composite granules; S4 UV curing: The composite granules are cured under UV light for 3-5 minutes to obtain toughened and impact-resistant nylon-based engineering plastics.

2. The preparation method according to claim 1, characterized in that, The average molecular weight of the polyacrylic acid is 5000.

3. The preparation method according to claim 1, characterized in that, The photoinitiator is 1-hydroxycyclohexylphenyl ketone.

4. The preparation method according to claim 1, characterized in that, The silane coupling agent is selected from one or more of KH550, KH560, and KH570.

5. The preparation method according to claim 1, characterized in that, The nylon resin is PA6 or PA66.

6. The preparation method according to claim 1, characterized in that, The twin-screw extruder has the following temperatures: Zone 1 220-230℃, Zone 2 230-240℃, Zone 3 240-250℃, Zone 4 235-245℃, and Die Head 240-250℃. The screw speed is 250-350 r / min.

7. The preparation method according to claim 1, characterized in that, The antioxidant is one or a combination of two of antioxidants 1098 and antioxidant 168; the lubricant is ethylene bis-stearamide or calcium stearate.

8. A toughened and impact-resistant nylon-based engineering plastic, characterized in that, Prepared by the method described in any one of claims 1-7.

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